On the eve of what's expected to be a tough confirmation hearing Thursday, one senator has thrown up a political roadblock intended to stymie Federal Reserve Chairman Ben Bernanke's second term.

Sen. Bernie Sanders, I-Vt., said late Wednesday that he will put a hold on Bernanke's nomination. A hold is an informal practice in which a senator informs the majority leader that he does not want a measure or nomination to reach the floor for a vote.